In the standard microcomputer data bus configuration, daughtercards are inserted into edge card connectors that allow for a mounting angle perpendicular to the plane of the motherboard. Whereas this configuration makes the most efficient use of space in a direction parallel to the plane of the motherboard and perpendicular to the faces of the daughtercards, it unfortunately maximizes the chassis dimension normal to the plane of the motherboard. In desktop computer designs, this represents no serious liability, since the chassis can be configured to accommodate this inherent bus characteristic simply by extending the height of the chassis as required. In a portable computer, however, since space is at a premium, an entirely new bus configuration is required to reduce the height of the chassis while yet maintaining reasonable inter-daughtercard distributions. Such a design would have the effect of reducing the thickness of a portable computer between 11/2 to 2 inches without recourse to eliminating daughtercards, the only viable alternative known to the prior art.
Rather than mount the daughtercards perpendicular to the motherboard, or horizontally across the board (resulting in serious heat dissipation problems, let alone bus transmission difficulties related to inordinate extension of the data path), the present invention comprises a daughtercard mounting configuration designed around an angular mounting geometry, one that permits the daughtercards to be securely mounted at a 30-degree angle up from the plane of the motherboard. An extension bus, in conjunction with the angular geometry of the card frame, permits a significant reduction in the overall thickness of a portable computer.